^ Truth is, you will be losing mass in your butt and hips because estrogen in women makes them keep fat in their lower bodies, and starting on T makes your body willing to lose that feminine fat. It has nothing to do with muscles or strength. I feel even a man's lower body should be stronger than a woman's regardless of whether they workout or not just because they can more easily build muscle, and those who do workout will usually have much stronger lower bodies than women. There's a reason men's thighs and calves are usually comparable in size to women's, if not bigger, and men's thighs are mostly muscle while women's are mostly fat.
Ever heard the term "skinny fat"? This is what I am. You can be SKINNY while still having a high body fat percentage. This just means the fat is evenly distributed over your body rather than in specific places like your gut. So there's a chance you ARE losing fat, not muscle. Although it is true that unless you start working out your muscles, they will atrophy over time and become smaller and weaker.
People always told me I was so skinny. But truthfully? Even at my smallest I still had at least 18% body fat, and was probably over 20% after having tried to feminize. Doesn't make me chubby or squishy, just means I have fat to lose before I see great muscle tone.
In the end, unless you've been on both ends of the spectrum, between flabby and muscular, you probably won't be able to tell the difference between losing fat and losing muscle. So just workout frequently and consume a good bit of protein and you'll make sure you're burning mostly fat and not muscle.
